This invention relates generally to improvements in infusion pumps of the type used for controlled delivery of medication to a patient. More specifically, this invention relates to an improved infusion pump and related medication-containing syringe, wherein the pump and syringe include matingly interfitting components to ensure pump use with a compatible and correctly installed syringe.
Infusion pump devices and systems are relatively well known in the medical arts, for use in delivering or dispensing a prescribed medication such as insulin to a patient. In one form, such devices comprise a relatively compact housing adapted to receive and support a syringe carrying a prescribed medication for administration to the patient through infusion tubing and an associated catheter or the like. The infusion pump includes a small drive motor connected via a lead screw assembly for motor-driven advancement of a syringe piston plunger to administer the medication to the patient. Programmable control means are normally provided for operating the drive motor continuously or at periodic intervals to obtain a closely controlled and accurate delivery of medication over an extended period of time. Such infusion pumps are utilized to administer insulin and other medications, with exemplary pump constructions being shown and described in U.S. Pat. Nos. 4,562,751; 4,678,408; 4,685,903; 4,562,751; 4,678,408; 4,685,903; 5,080,653; and 5,097,122, which are incorporated herein by reference.
Infusion pumps of the general type described above have provided significant advantages and benefits with respect to accurate delivery of medication over an extended time period. The infusion pump is often designed to be extremely compact and thus may be adapted to be carried by the patient, for example, by means of a belt clip or the like. As a result, important medication can be administered with precision and in an automated manner, without significant restriction on the patient's mobility or life-style.
To achieve accurate and reliable delivery of medication to the patient in response to motor-driven advancement of the syringe piston plunger, it can be extremely important to use a syringe which is designed to meet a narrow set of operational specifications which are compatible with the syringe pump. That is, variations in the size and shape of the syringe, friction forces attributable to sliding plunger seals, etc., can result in significant variations in the amount of medication administered in response to operation of the pump drive motor. In addition, incorrect installation of the syringe into the pump housing can result in undesirable inaccuracte delivery or nondelivery of the medication.
The present invention overcomes these problems and disadvantages by providing matingly interfitting components on the pump and the syringe to prevent pump usage with an incompatible syringe and further to ensure that the syringe is fully and correctly installed prior to use.